CN112697334A - Three-dimensional force touch sensor - Google Patents
Three-dimensional force touch sensor Download PDFInfo
- Publication number
- CN112697334A CN112697334A CN202011446998.XA CN202011446998A CN112697334A CN 112697334 A CN112697334 A CN 112697334A CN 202011446998 A CN202011446998 A CN 202011446998A CN 112697334 A CN112697334 A CN 112697334A
- Authority
- CN
- China
- Prior art keywords
- force
- circuit board
- flexible circuit
- dimensional force
- sensing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/16—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force
- G01L5/165—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force using variations in capacitance
Abstract
The invention relates to the technical field of bionic touch, in particular to a three-dimensional force touch sensor which comprises a flexible circuit board and at least one off-voltage force sensing structure, wherein the off-voltage force sensing structure and the flexible circuit board are arranged in a laminated manner; the electrode layer of the flexible circuit board comprises at least one sensing unit, and the sensing unit comprises at least four interdigital electrodes; the off-voltage force sensing structure comprises a bottom plate and a hemispherical protrusion integrally formed with the bottom plate, and the surface of the bottom plate, which is in contact with the sensing unit, is a rough surface. The three-dimensional force touch sensor provided by the invention solves the problems of complex structure, low sensitivity and poor three-dimensional force measurement precision of the conventional three-dimensional force touch sensor.
Description
Technical Field
The invention relates to the technical field of bionic touch, in particular to a three-dimensional force touch sensor.
Background
The most important function of electronic skin is tactile perception, which includes detecting various stimuli such as pressure, temperature, shear force, bending, vibration, sliding, and the like, and which has wide applications in the fields of wearable devices, robotics, and prostheses. In actual tactile perception of electronic skin, three-dimensional force electronic skin capable of detecting and distinguishing normal force and tangential force is very important for simulating natural skin to realize real artificial intelligence touch. This will enable the electronic skin to encode richer information, making it closer to natural touch and having advanced sensing capabilities. In addition, accurate sensing of normal and tangential forces is critical for gentle grasping and manipulation of objects on artificial fingertips in robotic-assisted surgical systems, and the sensed friction or tickling can also cause the biomimetic robot to generate more emotional responses.
In recent years, researchers have been dedicated to developing three-dimensional force electronic skins and have made certain breakthrough, for example, the Beccai project group in italy develops a flexible three-dimensional force sensor based on the parallel plate capacitance principle, and under the action of tangential component force, four sensing points judge the magnitude and direction of three-dimensional force due to the difference of capacitance magnitudes caused by the inconsistency of the opposite areas of parallel plate capacitance. The domestic Xue subject group develops a 4X 4 three-dimensional force electronic skin based on a CNTs/PDMS piezoresistive nanocomposite material, four normal pressure sensing points are distributed on each sensing unit, the direction of force is judged according to the difference of output signals of the four sensing points caused by shearing force, and a sensing array with high spatial resolution cannot be realized due to the limited sensitivity and large volume of the sensing units. The U.S. Bao topic group developed capacitive e-skins (5 x 5 arrays) based on an asymmetric interlocking structure with each cell of the hemispherical array bottom electrode in contact with 25 micro-pyramid arrays in its top electrode. Due to the asymmetric interlocking geometry, 25 sensor pixels in each hemisphere will deform anisotropically under multidirectional pressure, thereby determining the magnitude and direction of the three-dimensional force. However, the preparation process of the electronic skin is complex and is not favorable for large-area integration. In addition, the electronic skin based on the typical parallel plate capacitive sensing principle has low sensitivity and is easily interfered by environmental noise.
The existing piezoresistive three-dimensional force electronic skin can judge the magnitude and direction of force according to the difference of pressures borne by four normal pressure sensing points under the action of shearing force. However, the piezoresistive sensing principle has the problems of slow response, low sensitivity, high noise, non-linear response and the like. The parallel plate capacitive three-dimensional force electronic skin causes the inconsistency of the relative areas of four sensing points under the action of tangential force to cause the difference of the capacitance, thereby detecting the magnitude and the direction of the force. The three-dimensional force electronic skin utilizing the sensing mechanism has the main defect that the capacitance value is small, generally several to dozens of pF, and the skin is easily interfered by external environment noise.
Disclosure of Invention
The invention provides a three-dimensional force touch sensor, which aims to solve the problems of complex structure, low sensitivity and poor three-dimensional force measurement precision of the conventional three-dimensional force touch sensor.
The technical scheme for solving the problems is as follows: the three-dimensional force touch sensor comprises a flexible circuit board and at least one off-voltage force sensing structure, wherein the off-voltage force sensing structure and the flexible circuit board are arranged in a laminated manner, and
the electrode layer of the flexible circuit board comprises at least one sensing unit, and the sensing unit comprises at least four interdigital electrodes;
the off-voltage pressure sensing structure comprises a bottom plate and a hemispherical protrusion integrally formed with the bottom plate, and the surface of the bottom plate, which is in contact with the sensing unit, is a rough surface.
Preferably, the ratio of the diameter of the hemispherical protrusion to the thickness of the base plate is in the range of 1-1000: 1.
Preferably, the ratio of the diameter of the hemispherical protrusion to the thickness of the base plate is in the range of 6-30: 1.
Preferably, the flexible circuit board is a flexible printed circuit multilayer board.
Preferably, a plurality of the sensing units form an interdigital electrode array, and the interdigital electrode array is arranged on the substrate of the flexible circuit board in a manner that one column or one row shares one bit line.
Preferably, the flexible circuit board further comprises a shielding layer, and the shielding layer is arranged on the electrode layer in a way of copper-common-ground coating.
Preferably, the piezoelectric force sensing structure is made of piezoelectric force sensing rubber.
Preferably, an adhesive is disposed at an edge of the off-voltage force sensing structure, and the off-voltage force sensing structure is adhered to the flexible circuit board through the adhesive.
Compared with the prior art, the invention has the beneficial effects that:
1) the three-dimensional force touch sensor provided by the invention has the characteristics of simple structure, high sensitivity, high signal-to-noise ratio and strong anti-interference performance.
2) The off-voltage force sensing structure comprises a bottom plate and a hemispherical bulge integrally formed with the bottom plate, wherein the hemispherical bulge is correspondingly deformed under the action of three-dimensional forces in different directions and different sizes, so that a sensing unit contacted with the bottom of the hemispherical bulge can sense different signals, and the magnitude and the direction of the output force can be judged.
Drawings
Fig. 1 is a schematic structural diagram of a three-dimensional force tactile sensor according to the present invention.
FIG. 2 shows the microstructure change of the interface before and after the force is applied to the piezoelectric force sensing structure.
Fig. 3 is a simulation diagram of the three-dimensional force tactile sensor receiving positive pressure.
Fig. 4 is a force-bearing simulation diagram of the three-dimensional force touch sensor.
Fig. 5 is a design schematic diagram of an interdigital electrode array.
In the figure: 1-a distance voltage sensing structure, 11-a bottom plate, 12-a hemispherical bulge, 2-a flexible circuit board and 21-a sensing unit.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.
The three-dimensional force touch sensor comprises a flexible circuit board 2 and at least one off-voltage force sensing structure 1, wherein the off-voltage force sensing structure 1 and the flexible circuit board 2 are arranged in a stacked manner, and
the electrode layer of the flexible circuit board 2 comprises at least one sensing unit 21, and the sensing unit 21 comprises at least four interdigital electrodes;
the off-voltage force sensing structure 1 comprises a bottom plate 11 and hemispherical protrusions 12 integrally formed with the bottom plate 11, the surface of the bottom plate 11, which is in contact with the sensing units 21, is a rough surface, when the off-voltage force sensing structure 1 is not stressed, the off-voltage force sensing structure 1 and the sensing units 21 are in a contact state, when the off-voltage force sensing structure 1 is stressed, the contact surface between the off-voltage force sensing structure 1 and the sensing units 21 is increased, and the sensor has a super-capacitor characteristic.
The invention provides a three-dimensional force touch sensor based on an off-voltage force sensing mechanism, which utilizes the capacitance change of an electrode-ion interface caused by external pressure load as shown in figure 2. After the ionization pressure sensing structure 1 is stressed, the electrode is contacted with ions to form a compact charge layer on the surface of the electrode, namely an Electric Double Layer (EDL), which has special super-capacitance characteristics, is a nano-scale capacitance structure formed by arranging ions and electrons and has a frequency as high as several mu F/cm in a sub-MHz spectrum2Ultra-high capacitance per Unit Area (UAC). By comparison, typical parallel plate capacitive sensors measure only tens to hundreds of pF/cm at similar dimensions2In the meantime.
The Electric Double Layer (EDL) capacitance of the sensor is proportional to the contact area between the ions and the electrode surface, which is related to mechanical deformation caused by external pressure loads. Three-dimensional force tactile sensors based on an off-voltage force sensing mechanism exhibit extremely high sensitivity and resolution, with negligible parasitic capacitance in view of their ultra-high signal-to-noise ratio (SNR). Therefore, the invention is based on an off-voltage force sensing mechanism, and has the advantages of high sensitivity, high resolution, strong anti-interference capability, low measurement noise, capability of detecting static and dynamic pressure, high linearity and the like.
As a preferred embodiment of the present invention, the ratio of the diameter of the hemispherical projected section 12 to the thickness of the bottom plate 11 is in the range of 1-1000:1, improving the sensitivity of the sensor.
As a preferred embodiment of the present invention, the ratio of the diameter of the hemispherical projected 12 to the thickness of the bottom plate 11 is in the range of 6-30: 1.
As a preferred embodiment of the present invention, the flexible circuit board 2 is a flexible printed circuit multilayer board.
As a preferred embodiment of the present invention, the plurality of sensing units 21 constitute an interdigital electrode array, which is disposed on the substrate of the flexible circuit board 2 in such a manner that one column or one row shares one bit line.
As a preferred embodiment of the present invention, the flexible circuit board 2 further includes a shielding layer, and the shielding layer is disposed on the electrode layer in a common-ground copper-clad manner, so as to reduce crosstalk caused by a large number of small-gap parallel routing manners, and improve interference resistance.
As a preferred embodiment of the present invention, the material of the piezoelectric force sensing structure 1 is piezoelectric force sensing rubber, which is the key for generating electrode-ion interface sensing, and they provide the free-moving ions required for piezoelectric force sensing.
As a preferred embodiment of the present invention, an adhesive is disposed at the edge of the piezoelectric force sensing structure 1, and the piezoelectric force sensing structure 1 is attached to the flexible circuit board 2 by the adhesive.
Example 1: fabrication of three-dimensional force touch sensor
As shown in fig. 1, the three-dimensional force tactile sensor includes a flexible circuit board 2 and an off-voltage force sensing device which are stacked.
1. Manufacturing a flexible circuit board 2
The flexible circuit board 2 comprises two electrode layers and two substrates, the electrode layers and the substrates are arranged in a staggered and laminated mode, the electrode layers comprise 16 sensing units 21, the 16 sensing units 21 form an interdigital electrode array, and the sensing units 21 comprise four interdigital electrodes.
The ultra-high density interdigital electrode array is prepared by a double-sided circuit routing mode, wherein the interdigital electrode array reduces the number of addressing lines in the mxn array from mxn to m + n by sharing one bit line for one column or one row, as shown in fig. 5.
Be equipped with the shielding layer on the electrode layer, the shielding layer adopts the mode of covering copper altogether to reduce and is walked the crosstalk that the line brought by the parallel of a large amount of minigaps of electrode layer, improves the interference killing feature.
2. Manufacturing of off-voltage force sensing structure array
The off-voltage force sensing structure array comprises a plurality of connected off-voltage force sensing structures 1, each off-voltage force sensing structure 1 comprises a bottom plate 11 and hemispherical protrusions 12 integrally formed with the bottom plate 11, and the surface of the bottom plate 11, which is in contact with the sensing units 21, is a rough surface. The piezoelectric force sensing structure 1 is made of piezoelectric force sensing rubber.
Preparing an ionization pressure sensing rubber material: adding an organic silicon elastomer precursor and a curing agent according to a standard mass ratio, adding a glycol solution of sodium chloride with the mass ratio of 1:1 to the organic silicon elastomer precursor, wherein the sodium chloride is dissolved in the glycol in advance to form a solution with the mass fraction of 5%, and adding silicon dioxide particles, wherein the mass of the silicon dioxide particles accounts for 50% of that of the organic silicon elastomer precursor. And (3) stirring the mixture by a glass rod by hand to uniformly mix the reagents, and then stirring the mixture for 5 minutes at 5000 revolutions per minute by using a centrifugal stirrer to fully mix the components to obtain the ionic rubber precursor slurry.
The uncured ionic rubber is poured into a mold which is processed by a CNC process in advance, and the mold is placed into an oven at the temperature of 80 ℃ for 1 hour. And taking out the mold, and separating the cured ionic rubber from the mold to obtain the structured ionic rubber sensing functional material.
3. Making a sensor
And coating a certain amount of adhesive at the edge of the voltage-isolated force sensing structure array and pasting the adhesive and the flexible circuit board 2 together to obtain the packaged sensor.
The working principle of the three-dimensional force tactile sensor is as follows:
the signal acquisition hardware of the three-dimensional force touch sensor traverses each sensing unit 21 in the array based on a scanning gating mode, sequentially outputs signals of each sensing node, and further realizes the analysis and graphical display of touch signals through software.
As shown in fig. 3 and 4, when the applied force is a normal force, the off-voltage force sensing structure 1 has a contact stress equivalent to that of the bottom four interdigital electrodes; when the applied force is at an angle to the normal, the electrode contact stress along the force direction is greater. The direction and the magnitude of the applied force can be obtained by comparing, analyzing and calculating the capacitance detected by the four interdigital electrodes, so that the detection of the three-dimensional force is realized.
Performance characterization of the three-dimensional force tactile sensor: the output signals of the three-dimensional force touch sensor skin under the action of forces in different directions are tested by using a data acquisition circuit based on the FPGA, and the direction of the applied force is judged by calculating the size of a self-defined parameter S through a matlab algorithm.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent flow transformations made by using the contents of the specification and the drawings, or applied directly or indirectly to other related systems, are included in the scope of the present invention.
Claims (8)
1. Three-dimensional force tactile sensor, characterized in that, comprises a flexible circuit board (2) and at least one off-voltage force sensing structure (1), wherein the off-voltage force sensing structure (1) and the flexible circuit board (2) are arranged in a stacked manner, wherein
The electrode layer of the flexible circuit board (2) comprises at least one sensing unit (21), and the sensing unit (21) comprises at least four interdigital electrodes;
the off-voltage force sensing structure (1) comprises a bottom plate (11) and hemispherical protrusions (12) integrally formed with the bottom plate (11), and the surface of the bottom plate (11) in contact with the sensing units (21) is a rough surface.
2. The three-dimensional force tactile sensor according to claim 1, wherein the ratio of the diameter of the hemispherical protrusion (12) to the thickness of the base plate (11) is in the range of 1-1000: 1.
3. The three-dimensional force tactile sensor according to claim 2, wherein the ratio of the diameter of the hemispherical protrusion (12) to the thickness of the base plate (11) is in the range of 6-30: 1.
4. The three-dimensional force tactile sensor according to any one of claims 1 to 3, wherein the flexible circuit board (2) is a flexible printed circuit multilayer board.
5. The three-dimensional force touch sensor according to any one of claims 1 to 3, characterized in that a plurality of said sensing units (21) constitute an interdigital electrode array, which is arranged on the substrate of said flexible circuit board (2) in such a way that one column or one row shares one bit line.
6. The three-dimensional force tactile sensor according to claim 4, wherein the flexible circuit board (2) further comprises a shielding layer disposed on the electrode layer in a manner of being commonly copper-clad.
7. The three-dimensional force touch sensor according to claim 1, wherein the piezoelectric force sensing structure (1) is made of piezoelectric force sensing rubber.
8. The three-dimensional force touch sensor according to claim 7, wherein an adhesive is disposed at the edge of the off-voltage force sensing structure (1), and the off-voltage force sensing structure (1) is adhered to the flexible circuit board (2) by the adhesive.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011446998.XA CN112697334B (en) | 2020-12-11 | 2020-12-11 | Three-dimensional force touch sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011446998.XA CN112697334B (en) | 2020-12-11 | 2020-12-11 | Three-dimensional force touch sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112697334A true CN112697334A (en) | 2021-04-23 |
| CN112697334B CN112697334B (en) | 2022-11-29 |
Family
ID=75508229
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011446998.XA Active CN112697334B (en) | 2020-12-11 | 2020-12-11 | Three-dimensional force touch sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112697334B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114414105A (en) * | 2021-12-15 | 2022-04-29 | 中国科学院深圳先进技术研究院 | Conformal electronic skin |
| WO2023108462A1 (en) * | 2021-12-15 | 2023-06-22 | 中国科学院深圳先进技术研究院 | Conformal electronic skin |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101231200A (en) * | 2008-02-29 | 2008-07-30 | 合肥工业大学 | Touch sensor based on flexible pressure-sensitive conductive rubber |
| CN102928137A (en) * | 2012-11-14 | 2013-02-13 | 合肥工业大学 | Four-interdigital-electrode type three-dimensional force contact sensor for artificial skin |
| US20140174189A1 (en) * | 2012-12-14 | 2014-06-26 | The Regents Of The University Of California | Droplet-based capacitive pressure sensor |
| CN103954382A (en) * | 2014-05-14 | 2014-07-30 | 合肥工业大学 | Dielectric-varied capacitive flexible three-dimensional force tactile sensor |
| CN107044891A (en) * | 2016-08-28 | 2017-08-15 | 美国钛晟科技股份有限公司 | Capacitance pressure transducer, based on ionic membrane |
| CN110358297A (en) * | 2018-12-29 | 2019-10-22 | 钛深科技(深圳)有限公司 | Ionic rubber elastomer and preparation method thereof, from electronic type electronic skin |
-
2020
- 2020-12-11 CN CN202011446998.XA patent/CN112697334B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101231200A (en) * | 2008-02-29 | 2008-07-30 | 合肥工业大学 | Touch sensor based on flexible pressure-sensitive conductive rubber |
| CN102928137A (en) * | 2012-11-14 | 2013-02-13 | 合肥工业大学 | Four-interdigital-electrode type three-dimensional force contact sensor for artificial skin |
| US20140174189A1 (en) * | 2012-12-14 | 2014-06-26 | The Regents Of The University Of California | Droplet-based capacitive pressure sensor |
| CN103954382A (en) * | 2014-05-14 | 2014-07-30 | 合肥工业大学 | Dielectric-varied capacitive flexible three-dimensional force tactile sensor |
| CN107044891A (en) * | 2016-08-28 | 2017-08-15 | 美国钛晟科技股份有限公司 | Capacitance pressure transducer, based on ionic membrane |
| CN110358297A (en) * | 2018-12-29 | 2019-10-22 | 钛深科技(深圳)有限公司 | Ionic rubber elastomer and preparation method thereof, from electronic type electronic skin |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114414105A (en) * | 2021-12-15 | 2022-04-29 | 中国科学院深圳先进技术研究院 | Conformal electronic skin |
| WO2023108462A1 (en) * | 2021-12-15 | 2023-06-22 | 中国科学院深圳先进技术研究院 | Conformal electronic skin |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112697334B (en) | 2022-11-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Zhang et al. | Highly sensitive flexible three-axis tactile sensors based on the interface contact resistance of microstructured graphene | |
| Chen et al. | Scalable imprinting of flexible multiplexed sensor arrays with distributed piezoelectricity‐enhanced micropillars for dynamic tactile sensing | |
| CN112697334B (en) | Three-dimensional force touch sensor | |
| Maslyczyk et al. | A highly sensitive multimodal capacitive tactile sensor | |
| CN111609953B (en) | Full-flexible capacitive three-dimensional force touch sensor based on spherical surface electrode | |
| Agrawal et al. | An Overview of Tactile Sensing | |
| Göger et al. | Tactile proximity sensors for robotic applications | |
| Dahiya et al. | Tactile sensing technologies | |
| CN112649128B (en) | Sensing device and method for measuring three-dimensional contact stress | |
| Sun et al. | A highly-sensitive flexible tactile sensor array utilizing piezoresistive carbon nanotube–polydimethylsiloxane composite | |
| CN109323782B (en) | Non-array super-capacitor type touch sensor and application thereof | |
| Hoang et al. | A highly flexible, stretchable and ultra-thin piezoresistive tactile sensor array using PAM/PEDOT: PSS hydrogel | |
| Zhang et al. | Highly sensitive capacitive pressure sensor with elastic metallized sponge | |
| Su et al. | Highly sensitive ionic pressure sensor based on concave meniscus for electronic skin | |
| CN112539863B (en) | Three-dimensional force flexible touch sensor and preparation method and decoupling method thereof | |
| Ge et al. | A capacitive and piezoresistive hybrid sensor for long‐distance proximity and wide‐range force detection in human–robot collaboration | |
| He et al. | A multi-layered touch-pressure sensing ionogel material suitable for sensing integrated actuations of soft robots | |
| Wang et al. | Highly sensitive and flexible three-dimensional force tactile sensor based on inverted pyramidal structure | |
| He et al. | FEM and experimental studies of flexible pressure sensors with micro-structured dielectric layers | |
| Kisić et al. | Capacitive force sensor fabricated in additive technology | |
| WO2022120795A1 (en) | Three-dimensional force tactile sensor | |
| Gu et al. | Smart structure with elastomeric contact surface for prosthetic fingertip sensitivity development | |
| CN115060406B (en) | Flexible off-electricity type three-dimensional force sensor and preparation method thereof | |
| Wang et al. | Decoupling research of a three-dimensional force tactile sensor based on radical basis function neural network | |
| CN112362201A (en) | Positive octagonal frustum piezoresistive flexible touch sensor array and working method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |